Chronic prostatitis/Chronic pelvic pain syndrome (CP/CPPS) is a debilitating medical condition characterized by dysuria and pain in the perineum, testes, penis and suprapubic region. Prostatitis affects nearly 2 million people annually in the United States with 90% of all cases receiving a diagnosis of CPPS. The initiating factors that establish the syndrome are unknown. In our previous studies we have identified a key protease - mast cell tryptase and its cognate receptor protease activated receptor-2 (PAR2) as important players in disease pathogenesis in the experimental autoimmune prostatitis (EAP) animal model. PAR2 is the only known cognate receptor for mast cell tryptase, the key protease that was observed in our studies to be significantly elevated in prostatic secretions of CP/CPPS patients. In the prostate, the development of pelvic pain requires the mast cell tryptase-PAR2 axis and we show that tryptase-PAR2 activation leads to sensitization of neurons at the dorsal root ganglia (DRG). PAR2 deficient mice showed attenuated pelvic pain and an absence of DRG sensitization. The studies proposed in this project will build on these previous observations to identify the mechanism underlying PAR2-mediated peripheral sensitization and examine how peripheral mechanisms feed into the maintenance of chronic pelvic pain. Furthermore, we propose to define a novel role for the tryptase-PAR2 axis in EAP with regard to fibrosis and LUTS. Using the EAP animal model we observed increased markers of fibrosis and the presence of urinary dysfunction that were linked to PAR2 signaling. These results suggest a critical role for the tryptase- PAR2 axis in mediating urinary symptoms in EAP. We therefore hypothesize that mast cell tryptase-PAR2 signaling mediates the development and maintenance of pelvic pain and promotes mechanisms of prostate fibrosis that result in the development of LUTS. Finally we propose a translational aim where we will perform proof of concept pilot studies in human patients to identify whether therapeutic intervention is capable of reducing mast cell tryptase and influencing chronic pelvic pain and LUTS. These studies have the potential to have a significant impact on our understanding of CP/CPPS pathogenesis and to develop targeted therapies for patients.